3. Brush a 13 x 9-inch pan with a bit of the melted butter. Place a phyllo sheet on bottom of pan; brush with more melted butter. Continue layering sheets, brushing each with butter, until there is a stack of 10. Spread spinach mixture evenly on top (drain before doing so if more liquid has accumulated). Layer the remaining 10 sheets, brushing each with butter. Score spanakopita into 12 squares. Bake at 350 degrees for 45 minutes or until golden. Let stand 10 minutes, then slice into squares along scored lines.